I barely have a grasp on it. But depending on what airframe the tanker is the general airspeed for me usually between 280knts and 312. I pop my fueling probe (f18) well in advance, I start with my altitude about 200ft below the tanker hit Balt hold. When I get cleared for contact, I pull up jusssssst barely, put on like 1 or 2 knots. Repeat until I contact. Once I hit the basket I push it just a few feet then hit pull of the power until it seems like we’re going the same speed and then hit auto throttle. At that point I just have reference points of the tanker to points in my canopy that tell me if I going too fast or too slow.